This invention relates generally to steering columns and more particularly to steering columns having telescoping steering shafts supported in sleeves.
During operation of motor vehicles, road defects are transmitted through the wheels to the suspension and vehicle chassis as powerful shocks which, if transmitted to the steering wheel and the operator's hands, are objectionable and even harmful. This is addressed by providing a compliant structure, consisting of a slider steering shaft and a supporting sleeve, in the steering column which accommodates the chassis shocks and prevents them from reaching the steering wheel. Clearance is provided between the steering shaft and the supporting sleeve, in order to accommodate telescoping motion between the shaft and sleeve. This clearance results in an objectionable degree of rotational lash between the shaft and sleeve. Lubricant is commonly applied to the members to prevent axial binding. This lubricant fills the clearance when the assembly is new, but during the service life of the assembly, the lubricant is squeezed out of the corners due to the repeated alternating rotations of the shaft. The result is an increase of rotational lash, which is objectionable to the operators of the vehicle in which the steering column is installed.
There are many methods of addressing the rotational lash inherent in such assemblies. These commonly include placing a synthetic bushing or insert between the sliding members. The synthetic insert is lubricious and is far more resistant to the squeezing forces which expel viscous liquid lubricants from the corners. As a result, the increase of rotational lash is delayed and retarded; however, there is still some initial lash, even in well-fitted shaft, insert, and sleeve combinations. Many of such synthetic inserts are molded-in-place on the shaft end, for improved cost and assembly efficiency.
The foregoing illustrates limitations known to exist in present steering columns having telescoping steering shaft and sleeve assemblies. Thus, it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.